Piezoelectric ceramic, method of manufacturing same, and piezoelectric ceramic speaker using same

Patent metadata

Field	Value
Publication number	US-9786833-B2
Application number	US-201414522280-A
Country	US
Kind code	B2
Filing date	Oct 23, 2014
Priority date	Nov 8, 2013
Publication date	Oct 10, 2017
Grant date	Oct 10, 2017

Abstract

A piezoelectric ceramic has a primary phase constituted by ceramic grains of perovskite crystal structure containing Pb, Nb, Zn, Ti, and Zr, and a secondary phase constituted by ZnO grains present sporadically in the primary phase. The piezoelectric ceramic of high kr and high specific dielectric constant can be sintered at low temperature and exhibit minimal characteristics variations.

First claim

We claim:

1. A piezoelectric ceramic having a primary phase constituted by ceramic grains of perovskite crystal structure containing Pb, Nb, Zn, Ti, and Zr, and a secondary phase constituted by ZnO grains, wherein the primary phase is constituted by ceramic grains expressed by a composition formula Pb{(Zr (1-a) Ti a ) x ·(Ni 1/3 Nb 2/3 ) y ·(Zn 1/3 Nb 2/3 ) Z }O 3 (where 0<x≦0.85, 0≦y<1, 0<z<1, x+y+z=1, and 0.45≦a≦0.60).

2. A piezoelectric ceramic according to claim 1 , wherein the secondary phase is sporadically present randomly in the primary phase consisting essentially of the ceramic grains of perovskite crystal structure, and the secondary phase consists essentially of ZnO.

3. A piezoelectric ceramic according to claim 1 , wherein an average size of the ZnO grains is 0.4 to 1.6 μm.

4. A piezoelectric ceramic according to claim 1 , wherein the secondary phase accounts for about 0.2 to about 0.25 parts by weight relative to 100 parts by weight of the primary phase.

5. A piezoelectric ceramic according to claim 1 , wherein x and y as mentioned above are in ranges of 0<x<0.75 and 0<y<1.

6. A method of manufacturing piezoelectric ceramic having a primary phase constituted by ceramic grains of perovskite crystal structure containing Pb, Nb, Zn, Ti, and Zr, and a secondary phase constituted by ZnO grains, wherein the primary phase is constituted by ceramic grains expressed by a composition formula Pb{(Zr (1-a) Ti a ) x ·(Ni 1/3 Nb 2/3 ) y ·(Zn 1/3 Nb 2/3 ) Z }O 3 (where 0<x≦0.85, 0≦y<1, 0<z<1, x+y+z=1, and 0.45≦a≦0.60), said method comprising:
a step to obtain a composition constituted by ceramic grains of perovskite crystal structure expressed by formula Pb{(Zr (1-a) Ti a ) x ·(Ni 1/3 Nb 2/3 ) y ·(Zn 1/3 Nb 2/3 ) Z }O 3 (where 0<x≦0.85, 0≦y<1, 0<z<1, x+y+z=1, and 0.45≦a≦0.60); and
a step to mix the obtained composition with ZnO grains and then compact and sinter the mixture.

7. A manufacturing method according to claim 6 , wherein x and y as mentioned above are in ranges of 0<x<0.75 and 0<y<1.

Assignees

• Taiyo Yuden Kk

Inventors

• Watanabe Gouki
• Goto Takayuki
• Hatano Keiichi
• Kishimoto Sumiaki
• Doshida Yutaka

Classifications

• C04B35/64

  Burning or sintering processes (C04B33/32 takes precedence {; powder metallurgy B22F}) · CPC title

• C04B2235/3255

  Niobates or tantalates, e.g. silver niobate · CPC title

• C04B2235/3284

  Zinc oxides, zincates, cadmium oxides, cadmiates, mercury oxides, mercurates or oxide forming salts thereof · CPC title

• H04R31/00

  Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor {(manufacture of microstructural arrangements of deformable or non-deformable structures in general B81C1/00182)} · CPC title

• Y10T428/239

  Complete cover or casing · CPC title